1. Field of the Invention
The present invention relates to a white organic light emitting device.
2. Description of the Related Art
Generally, organic light emitting devices (OLEDs) which are spontaneous emission devices that emit light by recombination of electrons and holes in an organic layer, have the advantages of high color reproducibility, fast response speed, small thickness, high contrast ratio, wide viewing angle and low power consumption. OLEDS may be used in various fields such as display devices and illumination devices.
A white OLED, which is a thin light source, is advantageous to high resolution and large scale using an open mask instead of a high definition mask, and may be used in a backlight of a liquid crystal display (LCD) or a full color display device employing a color filter. In order to increase luminous efficiency of the white OLED, many stack type structures in which several unit OLEDs are connected in series in a vertical direction have been researched.
The main objective of the white OLED is to realize white light having color coordinates (0.31, 0.31). A top emission type white OLED has a structure in which a reflective layer is disposed under a emission structure having a thickness of about 100-200 nm and white light is emitted to an upper portion of the emission structure. An optical path control layer (OPCL) for effectively extracting internal light is disposed above the emission structure in which white light is emitted. As the thickness of the OPCL increases, separation of peaks of red (R), green (G) and blue (B) light is improved and the color gamut is improved, or the peaks of R, G and B light are separated and intensities of the peaks are changed so that color coordinates are changed.